Fascinating Facts About Peregrines

A fine mist rolls in from Lake Michigan. It is a grey morning in Chicago in spring 2015, and 28 floors up Dacey Arashiba is groggily following the smell of coffee. After pouring himself a cup he settles on his sofa for his morning ritual in front of the box. However, he’s not watching television, but a white plastic container hanging off his balcony railing that is occupied by the fastest animal in the world.

A peregrine is incubating her four eggs. From her lofty ledge she has a stunning view of downtown Chicago, all gleaming steel, glass and concrete. The male, or tiercel, is away hunting but Dacey expects that he’ll show up soon. Usually the female falcon spots his approach when he is no more than a distant dot in the sky, and lets out a volley of piercing cries in anticipation. “The key to hosting breeding peregrines seems to be an untended window box,” Dacey jokes – it seems that his lazy gardening has for once paid off.

The pair perform a food pass of a pigeon. Peregrines are expert fliers and incredibly fast, exceeding 350kph in controlled vertical dives when swooping on prey.

As Dacey documented his observations of’ Steve and Linda Perry’, as he calls his feathered neighbours, his social media accounts began to attract quite an audience. It was the remarkable pictures he posted online that brought the story to the attention of wildlife photographer Luke Massey, whose pictures accompany this article. “I actually first noticed the peregrines about four years ago,” says Dacey.

He explains that one morning he had walked into his kitchen and spotted something sitting outside the window. “It was a peregrine falcon!” His eyes light up. “The bird was just perched there, scanning the horizon. It turned its head and looked at me, and I looked at it. And then it flew away.”

Winged tenants – From that point on Dacey occasionally saw the peregrines resting on his balcony, or swooping by as they hunted, until in 2014 their visits became more frequent. “The birds took a bit of interest in the window box,” he says, but unfortunately tenants in the surrounding apartments complained about the noise. “So the maintenance team scattered some repellent powder and they disappeared.” However, the rainy Chicago spring washed the powder away and two months later the falcons returned.

When Dacey realised that they had laid eggs he got in touch with Mary Hennen, director of the Chicago Peregrine Program, and that was when he learned that the species was federally protected. Though neither of the peregrines were ringed, Mary recognised them as a pair that had consistently been choosing unsuitable nest sites around the neighbourhood – including a roof gutter, where their nest had washed away as soon as the rains had come.

So by the time the birds returned to Dacey s balcony and made a scrape in his empty window box in June 2014, it was too late in the season. The clutch was weak and in July sadly failed. In March 2015 the same pair of peregrines came back once more. The female created a scrape in the still-untended window box, and laid four eggs. Luke and I arrived on 11 May and immediately took our seats on Dacey s perfectly positioned sofa to begin our peregrine watch. Going from the laying dates – the first egg was laid on 13 April – the chicks were due to hatch any day.

A night-time photograph of the female and her brood. Helped by the city glow, urban peregrines are known to hunt after dark.

The two adults followed a strict routine of swapping incubating duties every four hours or so, amid much excited calling. If the tiercel was late, the female would fly out from the nest to the opposite building in search of him. Whichever bird was off-duty would disappear to hunt and stretch its wings, frequently perching on the facing tower-block to preen or rest. On 15 May the first egg-crack appeared, but Luke and I only glimpsed it for a second while the female shifted position to let the male take over incubation responsibilities. We waited with bated breath and, sure enough, we had our first view of an eyas, or fluffy chick, at 5.30pm on 16 May.

Feeding time – The second chick hatched the following day, and we noticed that the female offered more meat to the elder one; peregrine chicks don’t tend to feed in their first 24 hours, instead depending on the remnant yolk ingested just before hatching. The following day the third chick hatched; again the female favoured the older two. We thought it unlikely that the fourth egg would hatch, because it had been laid some time after the others, but on 20 May we were delighted to see four chicks in the window box.

Making sure that a hungry brood receives enough food is a major challenge for peregrine parents. Fortunately this family had a head start. “Chicago’s location right on Lake Michigan makes for a major corridor for migration,” explains local ornithologist Josh Engel. The flyway brings a stream of thousands of songbirds heading north from their southerly wintering areas. “At the precise moment that peregrine eggs are hatching in Chicago, lots of migrant birds are around. They’re a really important food source.”

As in the UK, urban peregrines in North America often hunt migratory birds after dark, targeting a surprisingly wide range of waders and songbirds. At our Chicago nest, there seemed to be plenty of food to go round, with regular deliveries of red-winged blackbirds, swifts and pigeons. Responsibilities at the nest now shifted – the female brooded the nestlings on her own while the male took on the role of sole hunter. Often he would deliver prey to her in a dramatic mid-air food pass near the nest.

On a few occasions when the male was not there to produce a meal on time and the female s calls for him went unheeded, she flew around the corner to where they had a rooftop cache and returned with stored food. The chicks grew rapidly and after a fortnight were already four times their hatching size. At three weeks of age, their flight feathers and body contours were starting to develop nicely. On 8 June Mary Hennen came to ring the chicks, and was able to identify them as three females and a male.

As in the UK, ringing studies have provided invaluable information about the life history of city-dwelling peregrines in North America. Mary told us that the adults tend to be year-round residents of the city – six pairs can now be found within 13knr. By contrast, the juveniles can make some epic journeys. For example, a female hatched in Chicago has been spotted in New York, while one of the city’s young males has been found in Ecuador. Ringing has also highlighted illegal persecution, which – again like in the UK – is very much an issue. The month before we arrived in Chicago, a female persons unknown.

Fledge for freedom – It was exciting to speculate where Dacey’s high-rise brood might next be spotted, but before that they had to fledge successfully. It seemed that the chicks had enjoyed their taste of freedom while being ringed, because two days afterwards a couple of the females escaped the confines of the ever-more-crowded window box, moving to the floor of the balcony. The biggest fear was that these chicks would fledge prematurely and end up stuck or hurt. Not all peregrine eyries in Chicago are on skyscrapers – one is much lower, on Evanston Public Library just north of the city centre.

The female perches on the balcony of the nest site – note the chick in the window box. Peregrines breed when about two years old; clutches range from one to six eggs.

A pair have nested here for 10 years. “Nona and Squawker are beloved by residents of all ages,” says Karen Danczak Lyons, the library’s director. “Some Evanston residents even arrange their annual holiday around the fledging time.” The Evanston Library Fledge Watch runs shifts so that if recently fledged juveniles land somewhere unsafe the volunteers can return them to their ledge. Back at Dacey’s apartment, we watched as the youngest chick moved unsteadily from the window box to the balcony floor. It was a huge relief when the youngster made it. All four chicks used their new-found space to strengthen their wings with bouts of flapping, preparing for the next big step.

The moment finally arrived on 2 July as we gathered round Dacey’s computer, glued to the live feed from his peregrine webcam. The chicks were about to make their maiden flights. Within just two days, all four juveniles were throwing themselves into the job of learning how to be supreme aerial hunters, encouraged by their parents. The juveniles’ aerobatic chases and games of tag were thrilling yet deadly serious drills. Life is tough for young peregrines: roughly half of them don’t survive their first year.

However, if you’re a peregrine then Chicago is a good place to be. “If you look at the city’s buildings as pseudo cliffs, situated on an ample waterway, then it’s an ideal habitat,” Mary explains. Research suggests that the breeding success of peregrines in the USAs urban Mid-West (calculated as he average number of fledglings per nest) is among the highest anywhere in North America. Dacey s pair of peregrines are part of a much bigger success story for the raptor in Chicago.

The peregrine disappeared from the region completely in the years after World War II due to DDT poisoning – in fact by the 1960s none at all were left in the eastern USA. But the species was reintroduced in 1985, and has recovered brilliantly. “Peregrines are such a high-profile species – people get excited about them,” says Mary. “So our programme is able to draw on a big volunteer base – all of the people who live and work in buildings where the birds nest, and who love to follow their progress. The story of peregrines in Chicago is a fantastic springboard for environmental education and awareness.”